Preparation and properties of L-lactide-grafted sisal fiber-reinforced poly(lactic acid) composites

Pretreatment of the sisal fiber (SF) grafting with L-lactide (LA) monomer via a ring-opening polymerization catalyzed by a Sn(II)-based catalyst was performed to improve the interfacial adhesion between SF and poly (lactic acid) (PLA). Biocomposites from LA-grafted SF (SF-g-LA) and PLA were prepared by compression molding with fiber weight fraction of 10, 20, 30, and 40%, and then were investigated in contrast with alkali-treated sisal fiber (ASF) reinforced PLA composites and untreated SF reinforced PLA composites. PLA composites reinforced by half-and-half SF-g-LA/untreated SF (half SF-g-LA) were prepared and studied as well, considering the disadvantages of SF-g-LA. The results showed that both the tensile properties and flexural properties of the SF-g-LA reinforced PLA composites were improved noticeably as the introduction of SF-g-LA, compared with pure PLA, untreated SF reinforced PLA composites and ASF reinforced PLA composites. The mechanical properties of the half SF-g-LA reinforced PLA composites were not worse, even better in some aspects, than the SF-g-LA reinforced PLA composites. Fourier transform infrared analysis and differential scanning calorimetry analysis exhibited that both the chemical composition and crystal structure of the SFs changed after LA grafting. In addition, the fracture surface morphology of the composites was studied by scanning electron microscopy. The morphological studies demonstrated that a better adhesion between LA-grafted SF and PLA matrix was achieved. POLYM. COMPOS., 37:802-809, 2016. (c) 2014 Society of Plastics Engineers